英语改错 请找出下列句子中的错误,并改正.

英语改错 请找出下列句子中的错误,并改正.
1.I have bought the piano for six years.
2.where have you gone ---- I’ve gone to shool .
3.How many pages have you read by the end of last year
4.while I walked in the steet ,I saw my teacher .
5.They have had their lunch at tweleve
6.The workers have repaired the machines just now .
7.You have waited here since two hours